* {
  margin: 0;
  padding: 0;
}
body {
  height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
  background-color: #2c3e50;
}
.container {
  display: flex;
  justify-content: center;
  align-items: center;
  flex-direction: column;
  width: 300px;
  height: 450px;
  background-color: #34495e;
  border-radius: 40px;
  box-shadow: 15px 15px 10px rgba(33, 45, 58, 0.3);
  overflow: hidden;
  position: relative;
}
.container form {
  width: 400px;
  height: 200px;
  display: flex;
  justify-content: center;
  align-items: center;
  flex-direction: column;
}
.container form .tbx {
  width: 200px;
  height: 40px;
  outline: none;
  border: none;
  background: none;
  border-bottom: 1px solid #fff;
  margin: 10px;
  color: #fff;
  z-index: 1;
}
/* 设置placeholder */
.container form .tbx::placeholder {
  color: white;
  font-size: 15px;
}
.container form .btn {
  margin-top: 20px;
  width: 200px;
  height: 40px;
  outline: none;
  background: none;
  border: 1px solid white;
  border-radius: 20px;
  color: white;
  letter-spacing: 5px;
  /* 字间距 */
  z-index: 1;
}
.container h1 {
  z-index: 1;
  color: #ecf0f1;
  letter-spacing: 5px;
  font-size: 50px;
  font-weight: 100;
  text-shadow: 5px 5px 5px rgba(33, 45, 58, 0.3);
  /* ease-out:表示动画以低速结束。 */
  /* animation-fill-mode(定义元素动画结束以后或者未开始的元素样式) 
  （1）forwards:表示动画结束后，元素直接接使用当前样式。
  （2）backwards:表示在动画延迟时间元素使用关键帧中from的属性值或者to属性值（当animation-direction为reverse或者alternate-reverse时）   
  */
}
/* 设置鼠标进入的样式 */
.container .in {
  position: absolute;
  top: 0;
  left: 0;
  display: block;
  width: 0;
  height: 0;
  border-radius: 50%;
  background: #0099ff;
  transform: translate(-50%, -50%);
  animation: in 0.5s ease-out forwards;
}
/* 设置鼠标离开的样式 */
.container .out {
  position: absolute;
  top: 0;
  left: 0;
  display: block;
  width: 1200px;
  height: 1200px;
  border-radius: 50%;
  background: #0099ff;
  transform: translate(-50%, -50%);
  animation: out 0.5s ease-out forwards;
}
/* 设置鼠标进入时，元素的动画 */
@keyframes in {
  0% {
    width: 0;
    height: 0;
  }
  100% {
    width: 1200px;
    height: 1200px;
  }
}
/* 设置鼠标进入时，元素的动画 */
@keyframes out {
  0% {
    width: 1200px;
    height: 1200px;
  }
  100% {
    width: 0;
    height: 0;
  }
}
.container form .btn:hover {
  background-color: rgb(53, 53, 185);
}
